Waterfall vs. Spiral development and doc (was: RE: Why is working from a spec like walking on water?)

[Janet_Swisher -at- trilogy -dot- com]

gyaker -at- csc -dot- com wrote:

>Not to dig up a dead thread, but I'm curious of everyone's thoughts on 
this...
>I went to a software process seminar earlier this week that spoke to a 
number of
>my company's software development methodologies and our specific 
project's
>methodology. So it turns out there are two main camps of how software 
should be
>created. One states that you define the entire problem to be solved, 
write
>requirements, and write the software from the requirements. The other 
camp says
>the process proceeds more iteratively - where you work a little and 
refine your
>scope, work a little more, and keep refining your product (if I'm not 
100%
>accurate, someone should feel free to jump in and correct or clarify 
these
>concepts).

>So let me ask, is there any difference in the way that the documentation
>process should respond to each methodology employed?

The two development models you are referring to are commonly called the 
"waterfall" and the "spiral".  In the waterfall model, everything 
"cascades" from one phase to the next, and there is no going "uphill".  In 
the spiral model, the phases of development (requirements analysis, 
design, development, testing, etc.) are seen as a cycle, where the 
functionality and quality of the product are built up incrementally each 
time through the cycle, and each phase may be visited multiple times.

It seems to me that most of the discussion I've seen of documentation 
development assumes a waterfall model for both the product and the 
documentation.  I would also be very interested in hearing others' 
comments on documentation in a spiral-model environment.

Cheers,
Janet Swisher
Trilogy Software, Inc.